Passive integrated transponder tag with unitary antenna core

ABSTRACT

A passive integrated transponder (PIT) tag comprising an integrated circuit and a unitary core is described. The unitary core comprises a coil-forming portion proximate one end thereof and an integrated circuit support portion proximate an opposite end thereof. The integrated circuit support portion extends beneath and supports the integrated circuit.

This application is a continuation of U.S. Ser. No. 09/480,400, filedJan. 11, 2000, the contents of which are hereby incorporated byreference.

FIELD OF THE INVENTION

This invention relates to the field of passive integrated transpondertags, and specifically to a passive integrated transponder tag having aunitary antenna core.

BACKGROUND OF THE INVENTION

The use of Passive Integrated Transponder (PIT) tags which may beembedded in or attached to items to be tracked and accounted for hasbeen widespread for some time. These commonly known PIT tag systemsgenerally comprise one or more antenna coils so positioned as togenerate a field of radiated electromagnetic energy within which thetagged item or object must pass. As generally deployed, such systems areused to track and/or count animals within which a PIT tag has beensubcutaneously embedded or externally affixed.

As the PIT tag traverses the radiated field of electromagnetic energy,it is energized in a manner known in the art. The PIT tag uses thisenergy—which is typically stored in a capacitive element—to power atransmission circuit which emits a unique PIT tag identification signalthat is detected by the aforementioned antenna element. Theidentification signal detected by the antenna element is thentransmitted to remote processing equipment which decodes the detectedsignal and uses this decoded information for the purposes of counting,tracking or otherwise maintaining records pertinent to the population ofitems or animals being tracked by said system.

PIT tags, or transponders, of the type used for object identification,and particularly those which are implantable into living creatures, suchas livestock, are well known in the art. Most such PIT tags comprise acoil, which serves as a receiving antenna, for receiving interrogationsignals to activate the transponder and for receiving power for itsoperations. The same antenna is used to transmit the identificationsignal. An integrated circuit, housed in an art-recognized integratedcircuit package, is also provided for performing the circuit functions,including detection of the interrogation signal, conversion of thereceived signal to DC for powering of the transmitter operations,storage and provision of an identification code, generation of thetransmission signal frequency, and modulation of the transmitted signalin accordance with the code and its transmission. The circuit dividesthe interrogation signal frequency by plural divisors to generate twofrequencies which are used to provide a frequency-shift-keyed outputsignal, the transmission frequency varying in accordance with the storedidentification signal. The transponder may be encapsulated in glass or asimilarly durable material, as a matter of design choice. It may besupplied together with a disposable cannula for convenient syringeimplantation into an animal. Together with essentially conventionalinterrogator and data storage equipment, a complete animal monitoringsystem can be provided, suitable for monitoring migratory movements ofwild animals as well as laboratory animals, pets and livestock.

PIT tags of the type used for object identification, and particularlythose which are implantable into living creatures, such as livestock,are very small and have inherent size restrictions that must beconsidered in their design and manufacture. Over the years, differentsize PIT tags were tested and used throughout the industry. Eventually,in the market for animal identification through implantable PIT tagsespecially, the size became more standardized. Today, one of the morestandard sizes in this field is a PIT tag 12 mm long and 2.07 mm wide.Most of the major studies in companion animals and fish applicationswere carried out with such sized PIT tags. Given such a sizestandardization, a need in the art has arisen to increase the operatingrange or performance of the PIT tag without increasing its size.

As described in the prior art, PIT tags have generally been constructedin one of two ways. In the first, the PIT tags are built insubassemblies, such as one subassembly comprising the antenna havingloose wire leads and another subassembly comprising the IntegratedCircuit (IC) and a capacitor mounted on a Printed Circuit Board (PCB).See, for example, U.S. Pat. No. 5,211,129, which is assigned to the sameassignee as the present application, and which is hereby incorporated byreference. The two subassemblies are then electrically and mechanicallyconnected. This approach does provide some advantages, including the useof standard manufacturing machinery as well as the ability to permitdesign changes quickly and easily during the manufacturing process.However, this approach also has some disadvantages, such as it tends tobe labor intensive because much of the assembly of the subcomponentsmust be done manually, for example, connecting the antenna leads to theIC, and the entire manufacturing process tends to be costly and timelydue in part to the number of manufacturing steps involved.

In a second approach, the antenna leads are directly connected to the ICduring the manufacturing process. See for example, U.S. Pat. Nos.5,223,851 and 5,281,855, each of which is incorporated herein byreference. One advantage of such an approach is that the manufacturingprocess is more fully automated, thus saving time. However, due in partto the small size of the components involved, the machines that directlyconnect the antenna leads to the IC tend to be expensive and often needmaintenance or supervision by a dedicated expert. Further, anotherdisadvantage of this system is that because the antenna leads areconnected directly to the IC, it is difficult and expensive tosubstitute alternate types of ICs or capacitors on the final PIT tagwithout significant changes in the manufacturing assembly process.Nonetheless, in the prior art the core and IC support subassemblies arenot unitary but rather are multi-part assemblies made integral byjoining the parts together.

It would therefore be advantageous for a PIT tag to be developed whichwould alleviate shortcomings of the prior art. The present inventionprovides a solution.

SUMMARY OF THE INVENTION

The PIT tag of the present invention generally comprises a unitary corethat extends substantially the entire length of the PIT tag. As usedherein, the term unitary is given its ordinary meaning and means aone-piece core. In a preferred embodiment the unitary core generallycomprises a cylindrical portion for receiving the antenna coil at oneend and a flattened portion for permitting or housing the electricalconnection between the integrated circuit and/or capacitor and theantenna coil at the other end. In a preferred embodiment the flattenedportion of the core is formed with an integral pair of metalizationlayers or pads. With the core so constructed, the leads from the antennacoil can be electrically connected to the metalization layers during themanufacturing process. As discussed herein, it is assumed that theIntegrated Circuit (IC) is housed in an art-recognized IC package, thus,unless otherwise specified, the term IC as used herein refers not onlyto the circuitry but to the IC package and leads typically present withICs used in conjunction with the PIT technology described herein.

By providing metalization layers on the core itself, the integratedcircuit and/or capacitor can be easily electrically connected to themetalization layers in any of a number of art-recognized methods. Onceconnected to the metalization layers, the integrated circuit iselectrically connected to the antenna coil as well. With the core soconstructed, the unitary core serves as the support for the integratedcircuit and/or capacitor and also permits the electrical connectionbetween the integrated circuit and/or capacitor and the antenna coil tobe accomplished in a quicker and less costly manner than that of theprior art.

As one of skill in the art will recognize, by electrically connectingthe antenna coil to the metalization layer, as opposed to the integratedcircuit, machinery can be more readily utilized and the manufacturingprocess can be more fully automated. Further, by electrically connectingthe integrated circuit to the metalization layer, without having toattach the integrated circuit directly to the antenna coil leads, itbecomes easier and less expensive to customize the PIT tags bypermitting the substitution of different integrated circuits and/orcapacitors on the metalization layer, thereby permitting customized PITtags to be manufactured more easily.

Further, the unitary core of the present invention permits a largervolume of core material to be used in a standard-sized PIT tag, or anysize of PIT tag for that matter. As one of skill in the art willrecognize, one of the factors affecting the strength of anelectromagnetic field is the size and material of the core. Byincreasing the amount of core material in the PIT tag, withoutincreasing the overall size of the PIT tag, the PIT tag of the presentinvention provides for greater strength of the magnetic filed of theantenna coil, thereby increasing the operational range of the PIT tag.

Further, as one of skill in the art will recognize, by utilizing aunitary core design as described herein, the PIT tag may be able tosustain more shock and vibration than conventional PIT tags because theflattened portion of the core physically supports the integrated circuitand/or capacitor.

Further, as one of skill in the art will recognize, by utilizing aunitary core design as described herein, the integrated circuit used inthe PIT tag can be of the flip-chip technology with a surface mountingcapacitor connected with conductive glue and cured with heat, or withconventional soldering, or any other art-recognized method.

Other objects and features of the present invention will become apparentfrom the following detailed description considering conjunction with theaccompanying drawing figures. It is to be understood, however, that thedrawings, which are not to scale, are designed solely for the purpose ofillustration and not as a definition of the limits of the invention, forwhich reference should be made to the appended claims.

DESCRIPTION OF THE DRAWING FIGURES

In the drawing figures, which are not to scale, and which are merelyillustrative, and wherein like reference numerals depict like elementsthroughout the several views:

FIG. 1. is a top plan view of a unitary core for use in a PIT tag inaccordance with the present invention;

FIG. 2A is a front elevational view of the unitary core of FIG. 1;

FIG. 2B is a right side elevational view of the unitary core of FIG. 2A;

FIG. 3 is a bottom plan view of the unitary core of FIG. 1;

FIG. 4 is a top plan view of an antenna for use with the unitary core ofthe present invention;

FIG. 5 is a top plan view of a capacitor for use with the unitary coreof the present invention;

FIG. 6 is a top plan view of an integrated circuit for use with theunitary core of the present invention;

FIG. 7 is a top plan view of an encapsulating means for use with theunitary core of the present invention;

FIG. 8 is a top plan view of an assembled PIT tag in accordance with thepresent invention;

FIG. 9A is a front elevational view of the PIT tag of FIG. 8;

FIG. 9B is a right side elevational view of the PIT tag of FIG. 9A;

FIG. 10 is a bottom plan view of the PIT tag of FIG. 8;

FIG. 11 is a front elevational view of a Printed Circuit Board (PCB)having a capacitor and integrated circuit mounted thereon in accordancewith the present invention; and

FIG. 12 is a top plan view of the PCB of FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With initial reference to FIGS. 1-3, there is depicted a unitary core,generally depicted as 12, in accordance with the present invention. Asseen in FIGS. 1-3, the unitary core of the present invention generallycomprises a coil-forming portion 16 at one end of the core, and anintegrated circuit support portion 18 at the other end of the core. Thecore forming portion 16 generally comprises a center portion 36 havingbeveled ends 40 leading to end portions 42. As seen in FIG. 1, centerportion 36 is of generally reduced diameter than end portions 42 so asto accommodate the coil 20 as described below. However, other shapedcoil forming portions are envisioned, as a matter of design choice,without departing from the spirit of the invention. Between thecoil-forming portion 16 and the integrated circuit support portion 18,there is a transition portion 44. While transition portion 44 isdepicted as a sloped surface, other shaped portions are envisioned, as amatter of design choice, without departing from the spirit of theinvention. In fact, transition portion 44 is not essential to the designof unitary core 12 and therefore unitary core 12 could be constructedwithout a transition portion without departing from the spirit of theinvention, although it is preferred that the overall height of the coreand IC be kept at a minimum to keep the PIT tag small.

In a preferred embodiment, as best seen in FIGS. 2A and 2B, integratedcircuit support portion 18 comprises a flattened plane having a lesserheight than that of coil forming portion 16, so as to accommodate theinstallation of the other components of the PIT tag without increasingthe overall size of the PIT tag. While integrated support portion 18 isdepicted as a flattened plane, other shapes or configurations areenvisioned without departing from the spirit of the invention, as amatter of application specific design choice. That is, other shapes ofthe integrated support portion 18 are envisioned so long as the overallheight of the PIT tag remains within an acceptable range for use in animplantable PIT tags.

In a preferred embodiment, integrated support portion 18 comprisesmetalization layers 26. Metalization layers 26 are formed of anart-recognized material having the necessary conductive properties toaccomplish the objectives of the present invention and, in a preferredembodiment, the metalization layers 26 are formed of silver. Otherprecious metals, such as gold, are also envisioned and believed to beusable as a matter of application specific design choice. As one ofskill in the art will recognize, and as described more fully below, themetalization layers 26 serve as the electrical connection between theantenna 20, integrated circuit 14 and capacitor 28. In a preferredembodiment, metalization layers 26 are deposited on integrated circuitsupport portion 18 in an art-recognized deposition technique. However,metalization layers 26 could be otherwise mounted on or formed on, orin, or as a part of, integrated circuit support portion 18 as a matterof design choice without departing from the spirit of the invention.Further, while metalization layers 26 are depicted as extending only aportion of the length of integrated circuit support portion 18, theactual length or shape of the layers is not an essential aspect of thepresent invention. For example, the metalization layers 26 could beformed as a plate or any other shape and size, as a matter of designchoice, without departing from the spirit of the invention.

In a preferred embodiment, the unitary core 12 is formed of a ferrite,and, in particular, high temperature ferrite. High temperature ferritemay or may not be necessary, as a matter of design choice, depending onhow metalization layers 26 are deposited on, or formed on or inintegrated circuit support portion 18. Further, while ferrite isenvisioned as a preferred core material of the present invention, otherare-recognized core materials now known or available in the future areenvisioned without departing from the spirit of the invention.

Many of the other main components of a conventional Passive IntegratedTransponder (PIT) tag are depicted in FIGS. 4-7. As used herein theterms Passive Integrated Transponder tags and/or PIT tags are usedsynonymously and are intended to mean any type of passive transponderwhich emits a signal in response to exposure to a radiatedelectromagnetic, electrical or magnetic energy field. Such tags arecommonly subcutaneously embedded in animals for the purpose of trackingand identifying them in such locations as zoos and farms, or in thewild. Such tags are also used for tagging fish and birds, as well asdomestic pets. As is known in the art, and as will become evident from afurther reading of the material below, systems such as the one describedherein, may be deployed in numerous applications and situations limitedonly by the imagination of the person of skill in the art. The unitarycore of the present invention may therefor be used in any applicationwherein transponders are placed on objects for tracking such objects asthey pass within or through the field of a bi-directional antenna whichenergizes the transponder and receives identifying signals therefrom. Asused herein, the terms object and item are used interchangeably and meanany PIT tagged entity, animate or inanimate.

FIG. 4 depicts a conventional antenna, generally indicated as 20,comprising a coil portion 22 and lead portions 24. Antennae for use inPIT tags are well known in the art. The particular wire used, or thenumber of turns in coil portion 22, is not an essential feature of thepresent invention. That is, the present invention envisions the use ofany art-recognized antenna wire, having the necessary number of turns,to accomplish the desired application specific features of theparticular PIT tag required. FIG. 5 depicts a capacitor, which, asdescribed later, may or may not form a part of the invention dependingin part on the specific integrated circuit utilized in the PIT tag. FIG.6 depicts an integrated circuit 14. Integrated circuits are well knownin the art and, like capacitor 28, the particular integrated circuit 14used in the present invention can be selected as a matter of designchoice, depending on the particular characteristics or features desiredin the PIT tag. In a preferred embodiment, integrated circuit 14 is anISO 11'784/11'785 Compliant Read-Only Contactless Identification Devicesold by E.M. Micro Electronic—Marrin S.A. under the item number H 4005.The particular characteristics and features of the preferred integratedcircuit 14 are described in E.M. Micro Electronic—Marrin S.A.'sIntegrated Circuit's product catalog under the item number H 4005, whichis hereby incorporated by reference. As explained in greater detail inthe product catalogue, the preferred integrated circuit 14 comprises anon-chip resonance capacitor and on-chip supply buffer capacitor, whichtherefore may eliminate the need for capacitor 28 as depicted in theFigures herein. Furthermore, as explained in greater detail in theproduct catalogue, the preferred integrated circuit 14 comprises bumpsfor permitting an electrical connection between the integrated circuitand the metalization layers 26 of the present invention.

FIG. 7 depicts an encapsulation means 34. In a preferred embodiment,encapsulation means 34 is formed of glass. However, as a matter ofdesign choice, any other art recognized non-porous, corrosion-resistantmaterial that is amenable to sterilization could be used as theencapsulation means 34 without departing from the spirit of theinvention. Glass encapsulation of transponders is within the skill ofthe art, as described for example in U.S. Pat. No. 3,935,612 to Fisheret al., which is hereby incorporated by reference.

FIGS. 8-10 depict an encapsulated PIT tag having a unitary coreconstructed in accordance with a preferred embodiment of the presentinvention. As seen in FIGS. 8-10, coil portion 22 of coil 20 is woundabout coil-forming portion 16 of the unitary core 12, with the leadportions 24 extending from the coil portion in a direction towards theintegrated circuit support portion 18 of unitary core 12. The leadportions 24 terminate and are electrically connected to the metalizationlayers 26 in an art-recognized manner. Further, the capacitor 28, ifrequired, as well as the integrated circuit 14 are mounted and/orelectrically connected to the metalization layers 26. While capacitor 28is depicted in the Figures, as described above, the need for a capacitormay be eliminated, as a matter of design choice, depending on theparticular integrated circuit chosen. In a preferred embodiment, asdescribed above, the bumps on the preferred integrated circuit providefor the electrical connection between the integrated circuit 14 andmetalization layers 26. Other art-recognized methods or means forelectrically connecting the integrated circuit and/or the capacitor tothe metalization layers are envisioned without departing from the spiritof the invention.

As best seen in FIGS. 9A and 9B, the integrated circuit support portion18 of unitary core 12 extends beneath and supports the capacitor 28 andintegrated circuit 14. Further, because the integrated circuit supportportion 18 is formed with a reduced height (as compared with the coilforming portion 16) the overall height of the PIT tag need not beincreased when the integrated circuit 14 and/or capacitor 28 are mountedon the integrated circuit support portion 18 of unitary core 12. Also,as seen in FIG. 8-10, in a preferred embodiment unitary core 12 extendssubstantially the entire length of the interior of encapsulation means34.

In an alternate embodiment (not shown), unitary core 12 is constructedin a similar manner as described above, but metalization layers 26 arenot used. Instead, in the alternate embodiment, a Printed Circuit Board(PCB) 30 is used to electrically connect the antenna leads 24, capacitor28 and integrated circuit 14. As seen in FIGS. 11 and 12, the PCBcomprises electrical pads 32 to electrically connect the antenna leads24 of the antenna coil 20 to both the capacitor 28 an integrated circuit14, in a manner well known in the art. While the use of pads 32 aredepicted, other art-recognized methods or means of electricallyconnecting antenna leads 24 to PCB 30 are envisioned without departingfrom the spirit of the invention. In this alternate embodiment, the PCB30 is mounted on integrated circuit support portion 18 of unitary core12. Thus, as with the previous embodiment disclosed, the integratedcircuit support portion 18 of the unitary core 12 would extend beneathand support both the capacitor 28 and integrated circuit 14.

As one of skill in the art will recognize, the unitary core 12 of thepresent invention offers many advantages over prior art PIT tag cores.For example, by terminating the antenna lead 24 to the metalizationlayers 26, the manufacturing process could be more fully automated.Further, by electrically connecting the integrated circuit 14 to themetalization layers 26, without having to attach the integrated circuit14 directly to the antenna leads 24, it becomes easier and lessexpensive to customize the PIT tags by permitting the substitution ofdifferent integrated circuits and/or capacitors on the metalizationlayer, thereby permitting customized PIT tags to be manufactured moreeasily.

Further, as one of skill in the art will recognize, the unitary core ofthe present invention permits a larger volume of core material to beused in a standard sized PIT tag. As one of skill in the art willrecognize, one of the factors effecting the strength of anelectromagnetic field is the size and material of the core. Byincreasing the amount of core material in the PIT tag, withoutincreasing the overall size of the PIT tag, the PIT tag of the presentinvention provides for a greater capture of the magnetic field of theantenna coil, thereby increasing the operational range of the PIT tag.In fact, the applicant determined that the structure of the PIT tag coreof the present invention can provide for up to a 50% increase in theoperational range of the PIT tag as compared with prior art PIT tags.

Further, as one of skill in the art will recognize, by utilizing theunitary core design as described herein, the PIT tag may be able tosustain more shock and vibration than conventional PIT tags because theintegrated circuit support portion 18 physically supports the integratedcircuit 14 and/or capacitor 28.

Thus, while there have been shown and described and pointed outfundamental novel features of the invention as applied to preferredembodiments thereof, it will be understood that various omissions andsubstitutions and changes in the form and details of the disclosedinvention may be made by those skilled in the art without departing fromthe spirit of the invention. It is the intention, therefore, to belimited only as indicated by the scope of the claims appended hereto.

1-11. (canceled)
 12. A method of manufacturing a passive integratedtransponder tag having a unitary antenna core, said method comprising:providing a core of magnetic ferrite, which extends substantially thelength of said passive integrated transponder tag, having a coilreceiving portion and an electronics support portion; providing anantenna having a coil portion and a pair of lead portions, wherein saidcoil portion is wound around said coil receiving portion of said core ina direction towards said electronics support portion; electricallyconnecting said pair of lead portions to said electronics supportportion.
 13. The method of claim 12, further comprising: encapsulatingsaid core with an encapsulation means.
 14. The method of claim 12,wherein said electronics support portion comprises a metalization layertherein or thereon.
 15. The method of claim 14, wherein saidelectrically connecting said pair of lead portions to said electronicssupport portion comprises electrically connecting said pair of leadportions to said metalization layer.
 16. The method of claim 14, whereinsaid metalization layer is formed of a precious metal.
 17. The method ofclaim 16, wherein said precious metal is silver.
 18. The method of claim16, wherein said precious metal is gold.
 19. The method of claim 12,wherein said electronics support portion comprises one or more metalpads formed therein or thereon.
 20. The method of claim 19, wherein saidelectrically connecting said pair of lead portions to said electronicssupport portion comprises electrically connecting said pair of leadportions to said one or more metal pads.
 21. The method of claim 12,further comprising: providing an integrated circuit, wherein saidintegrated circuit is supported by said electronics support portion. 22.The method of claim 21, wherein said electrically connecting said pairof lead portions to said electronics support portion compriseselectrically connecting said pair of lead portions to said integratedcircuit.
 23. The method of claim 22, wherein said integrated circuit iselectrically connected to a metalization layer of said electronicssupport portion.
 24. The method of claim 22, wherein said integratedcircuit is electrically connected to said electronics support portionusing flip-chip technology.
 25. The method of claim 22, wherein saidintegrated circuit comprises one or more bumps for providing anelectrical connecting between said integrated circuit and a metalizationlayer of said electronics support portion.
 26. The method of claim 12,further comprising: mounting a capacitor on said electronics supportportion.
 27. The method of claim 12, wherein said electronics supportportion comprises a printed circuit board.
 28. The method of claim 27,wherein said electrically connecting said pair of lead portions to saidelectronics support portion comprises electrically connecting said pairof lead portions to said printed circuit board.
 29. The method of claim27, wherein said printed circuit board comprises one or more electricalpads for electrically connecting said printed circuit board to said pairof lead portions.